1. Field of the Invention
The present invention relates to a mask set for compensating a misalignment between patterns and a method of compensating a misalignment between patterns using the same. In particular, the present invention relates to mask set for compensating for a misalignment between patterns and method of compensating for a misalignment between patterns using mask set.
2. Description of the Prior Art
Generally, in the process of manufacturing a semiconductor device, a mask process of ten through thirty steps is required in order to form an impurity diffusion region, a contact hole and a conductive pattern. As semiconductor devices become higher integrated, a process margin between the patterns becomes more narrow. In the lithography process of forming a contact hole or a conductive pattern during the process of manufacturing the semiconductor device, there occurs a misalignment between the underlying and the upper patterns due to a misalignment occurring when the mask and the wafer are loaded into the exposure equipment and an alignment error of the exposure equipment itself. Though it does not cause a problem when the process margin between the underlying pattern and the upper pattern is great, when a contact hole is formed between the underlying and the upper patterns when the process margin therebetween is small, these patterns are likely to be exposed or part of them are likely to be etched, thereby resulting in reduction of reliability of the semiconductor device.
In order to solve these problems, a conventional method is to insert an alignment mark into a mask and/or a wafer and then monitor the alignment mark at the exposure equipment so as to compensate for a misalignment of the mask and/or the wafer. Also an alignment error of the exposure equipment itself in the conventional method is obtained in such a manner that it selects the mask having smallest process margin between the patterns among the masks for use in the manufacture process of a semiconductor device, forms patterns on a test wafer through the lithography process using these masks, and measures the alignment accuracy by means of the optical methods such as SEM or TEM etc. However, the measured values by this method are different for each person since they are obtained by each person's baked eye and further the time taken to perform one-time measurement is too long, thus it is extremely difficult to obtain statistical data. Especially, it is usually difficult to use the test wafer once the alignment accuracy of which is measured for other purpose since the sample thereof must be cut away the wafer in order to take a photograph of the cross-sectional SEM.